Adding a comment for revert validate. (#2234)

diff --git a/auto_submit/test/validations/revert_test.dart b/auto_submit/test/validations/revert_test.dart
index c81766e..36834eb 100644
--- a/auto_submit/test/validations/revert_test.dart
+++ b/auto_submit/test/validations/revert_test.dart
@@ -88,6 +88,7 @@
     });
 
     test('Link extraction from description returns null', () {
+      // input, expected
       Map<String, String> tests = <String, String>{};
       tests['Revert flutter/cocoon#123456'] = '';
       tests['revert flutter/cocoon#123456'] = '';